A collection of art seized by the Nazis in the 1930s and 1940s, and worth an estimated $1.35 billion, has been recovered in Munich, Germany.

The German magazineFocus revealed on Sunday that the collection of some 1,500 paintings includes works by Matisse, Picasso, Chagall and other modernist artists the Nazis considered as “degenerate.” Other pieces once belonged to Jewish collectors who had been forced to sell them for a pittance.

The trove was discovered by coincidence in early 2011 in a dusty, dark apartment belonging to a man who was being investigated for tax evasion. The man, who is now in his eighties, had made a living from occasional sales of lesser-known paintings.

A search has now begun for the heirs of the original owners, who under German law have the right to reclaim the art.